Diego is a Hood Island giant tortoise. Thought to have been hatched on Española Island, Galápagos, he was captured as a young adult and shipped to the United States where he was exhibited at zoos. By the late 1940s he was at San Diego Zoo, California, though his species was not known. A captive breeding effort for the critically endangered Hood Island tortoises was set up in 1976, by which time only 15 individuals were known to survive. Diego was identified as a Hood Island tortoise by DNA testing and was sent to Santa Cruz Island to join the programme. Diego fathered more than 900 offspring who were released on Española which helped to increase the wild population to more than 2,000. The breeding programme ended in January 2020 and Diego is officially retired, and released into the wild in June 2020.